1. Technical Field
The present invention relates to a recording method and an ink jet printer.
2. Related Art
The ink jet printer forms, for example, dots on a printing material by a plurality of nozzles lined up in a predetermined nozzle arrangement direction and the printing material being relatively moved in a scanning direction orthogonal to the nozzle arrangement direction, and ink droplets being discharged from the nozzles in accordance with recording data indicating the presence or absence of dots for each pixel. As the printing method, there is interlace printing or the like in which ink droplets discharged from adjacent nozzles in the nozzle arrangement direction are landed on non-adjacent pixels in the transport direction, and ink droplets are landed with respect to pixels between positions on which ink droplets are temporally not landed at a later pass (main scanning) (JP-A-2003-320661).
When the ink droplets are not discharged from the nozzles due to clogging or the like, or the discharged ink droplets do not trace the correct path, a “missing dot” region in which pixels on which dots are not formed are connected is formed, and stripes of the base color of the printing material, such as white stripes” arise in the printed image. In particular, when there is a defective nozzle, in which the discharging of the ink droplets is defective, in the K (black) nozzles, there is a tendency for the stripes of the base color of the printing material to be noticeable. Because interlace printing forms dots of adjacent pixels in the transport direction in different passes, the “missing dot” region may spread in the transport direction when there is an error in the paper feed amount. When the “missing dot” region spreads, the stripes of the base color of the printing material are easily noticed.
The ink jet printer disclosed in JP-A-2003-320661 is provided with a spare nozzle that are not used during normal printing at the end portion of the nozzle row, and ink droplets are discharged from the spare nozzles when the paper is transported in error more than the permitted amount. The technical concept of suppressing the noticeability of the stripes of the base color that occur in the printed image due to defective nozzles is not present in the technology disclosed in JP-A-2003-320661.
In a case of a defective nozzle being present in the K nozzles, forming composite black dots by discharging CMY ink droplets from each CMY (cyan, magenta, yellow) nozzle to the “missing dot” region in order to suppress the noticeability of the above-described stripes. However, it is difficult for each of the CMY dots to be completely superimposed, and colored stripes may be visible along the “missing dot” region. Because composite black dots appear lighter in color than single color black dots, a light stripe may be present along the “missing dot” region. This phenomenon easily arises in cases in which the printing method is interlace printing.
Problems such as the above are not limited to cases of interlace printing, and are similarly present in various ink jet printers.